Re: Response time increases over time

I have moved the data directory (xlog, base, global, and everything) to an
ext4 file system. The result hasn't changed unfortuately. With the same
load test the average response time: 80ms; from 40ms to 120 ms everything
occurs.
This ext4 has default settings in fstab.
Have you got any other idea what is going on here?

Thanks,
Otto

2011/12/8 Marti Raudsepp <marti(at)juffo(dot)org>

> On Thu, Dec 8, 2011 at 06:37, Aidan Van Dyk <aidan(at)highrise(dot)ca> wrote:
> > Let me guess, debian squeeze, with data and xlog on both on a single
> > ext3 filesystem, and the fsync done by your commit (xlog) is flushing
> > all the dirty data of the entire filesystem (including PG data writes)
> > out before it can return...
>
> This is fixed with the data=writeback mount option, right?
> (If it's the root file system, you need to add
> rootfsflags=data=writeback to your kernel boot flags)
>
> While this setting is safe and recommended for PostgreSQL and other
> transactional databases, it can cause garbage to appear in recently
> written files after a crash/power loss -- for applications that don't
> correctly fsync data to disk.
>
> Regards,
> Marti
>